1. Field of the Invention
The invention relates to a hybrid vehicle and, more particularly, to a hybrid vehicle that is provided with an engine capable of outputting power for traveling, a motor capable of outputting power for traveling, a first battery connected to a first electric power line to which the motor is connected, an automotive electrical instrument, a second battery connected to a second electric power line to which the automotive electrical instrument is connected, a DC/DC converter transforming electric power of the first electric power line and supplying the transformed electric power of the first electric power line to the second electric power line, and an alternator supplying electric power generated by driving by the engine to the second electric power line.
2. Description of Related Art
In the related art, a hybrid vehicle that is provided with an engine, a motor, a high-voltage battery, an automotive electrical component, a low-voltage battery, a DC/DC converter, and an alternator is disclosed as this type of hybrid vehicle (for example, refer to Japanese Patent Application Publication No. 2006-280110). The engine and the motor output power for traveling. The high-voltage battery supplies electric power to the motor. The low-voltage battery supplies electric power to the automotive electrical component. The DC/DC converter steps down the electric power from the high-voltage battery and supplies the electric power to the low-voltage battery and the automotive electrical component. The alternator is driven by the engine. The alternator supplies generated electric power to the low-voltage battery and the automotive electrical component. In this apparatus, the electric power that is supplied from the DC/DC converter is supplied to the low-voltage battery and the automotive electrical component when the amount of electric power consumption by the automotive electrical component is not so large. When the automotive electrical component consumes a large amount of electric power, electric power that can be output from the DC/DC converter is supplied and the electric power that is generated by the alternator is supplied to the automotive electrical component and the low-voltage battery along with this electric power. Accordingly, even when the automotive electrical component consumes a large amount of electric power, a sufficient amount of electric power can be supplied to the automotive electrical component and the low-voltage battery and the low-voltage battery can be sufficiently charged.
The above-described hybrid vehicle, however, causes a reduction in energy efficiency in some cases. In general, the alternator has a low level of efficiency at a low output current level. Accordingly, when the portion of the electric power consumption by the automotive electrical component that is not compensated for by the electric power from the DC/DC converter is supplied from the alternator, the chance of the driving of the alternator at the low output current level increases and the energy efficiency is reduced.